对象未真正存储在HTTP会话中.它与会话ID链接，并实际上存储在Spring上下文内部.会话监听器用于在会话关闭后清除实例.参见 SessionScope JavaDoc.

The object is not really stored in HTTP session. It is linked with session id and actually stored inside of the Spring context. A session listener is used to clean instances once session is closed. See SessionScope JavaDoc.